Monday, June 24, 2013

JavaScript English Tutorials

JavaScript

is an interpreted computer programming language. It was originally implemented as part of web browsers so that client-side scripts could interact with the user, control the browser, communicate asynchronously, and alter the document content that was displayed. More recently, however, it has become common in both game development and the creation of desktop applications.

JavaScript is a prototype-based scripting language that is dynamic, is type safe, and has first-class functions. Its syntax was influenced by the language C. JavaScript copies many names and naming conventions from Java,
but the two languages are otherwise unrelated and have very different
semantics. The key design principles within JavaScript are taken from
the Self and Scheme programming languages. It is a multi-paradigm language, supporting object-oriented, imperative, and functional programming styles.

JavaScript's use in applications outside of web pages—for example, in PDF documents, site-specific browsers, and desktop widgets—is also significant. Newer and faster JavaScript VMs and frameworks built upon them (notably Node.js) have also increased the popularity of JavaScript for server-side web applications.

JavaScript was formalized in the ECMAScript language standard and is primarily used as part of a web browser (client-side JavaScript). This enables programmatic access to computational objects within a host environment.

History

Birth at Netscape

JavaScript was originally developed in Netscape, by Brendan Eich.
Battling with Microsoft over the Internet, Netscape considered their
client-server solution as a distributed OS, running a portable version
of Sun Microsystems' Java. Because Java was a competitor of C++ and aimed at professional programmers, Netscape also wanted a lightweight interpreted language that would complement Java by appealing to nonprofessional programmers, like Microsoft's Visual Basic (see JavaScript and Java).

Developed under the name Mocha, LiveScript was the
official name for the language when it first shipped in beta releases of
Netscape Navigator 2.0 in September 1995, but it was renamed JavaScript when it was deployed in the Netscape browser version 2.0B3.

The change of name from LiveScript to JavaScript roughly coincided with Netscape adding support for Java technology in its Netscape Navigator web browser. The final choice of name caused confusion, giving the impression that the language was a spin-off of the Java programming language,
and the choice has been characterized by many as a marketing ploy by
Netscape to give JavaScript the cachet of what was then the hot new web
programming language.

Server-side JavaScript

Netscape introduced an implementation of the language for server-side scripting (SSJS) with Netscape Enterprise Server, first released in December, 1994 (soon after releasing JavaScript for browsers). Since the mid-2000s, there has been a proliferation of server-side JavaScript implementations. Node.js is one recent notable example of server-side JavaScript being used in real-world applications.

Adoption by Microsoft

JavaScript very quickly gained widespread success as a client-side scripting language for web pages. Microsoft introduced JavaScript support in its own web browser, Internet Explorer, in version 3.0, released in August 1996 Microsoft's webserver, Internet Information Server,
introduced support for server-side scripting in JavaScript with release
3.0 (1996). Microsoft started to promote webpage scripting using the
umbrella term Dynamic HTML.

Microsoft's JavaScript implementation was later renamed JScript to avoid trademark issues. JScript added new date methods to fix the Y2K-problematic methods in JavaScript, which were based on Java's java.util.Date class.

Standardization

In November 1996, Netscape announced that it had submitted JavaScript to Ecma International for consideration as an industry standard, and subsequent work resulted in the standardized version named ECMAScript. In June 1997, Ecma International published the first edition of the ECMA-262 specification.
A year later, in June 1998, some modifications were made to adapt it to
the ISO/IEC-16262 standard, and the second edition was released. The
third edition of ECMA-262 (published on December 1999) is the version most browsers currently use.

Fourth edition of Ecmascript standard was not released and does not
exist. Fifth edition of the Ecmascript standard was released in December
2009. The current edition of Ecmascript standard is 5.1 and it was
released in June 2011.

Later developments

JavaScript has become one of the most popular programming languages
on the web. Initially, however, many professional programmers denigrated
the language because its target audience consisted of web authors and
other such "amateurs", among other reasons. The advent of Ajax
returned JavaScript to the spotlight and brought more professional
programming attention. The result was a proliferation of comprehensive frameworks and libraries,
improved JavaScript programming practices, and increased usage of
JavaScript outside of web browsers, as seen by the proliferation of server-side JavaScript platforms.

In January 2009, the CommonJS
project was founded with the goal of specifying a common standard
library mainly for JavaScript development outside the browser.